Rare-Earth Metals

A family of metals derived from certain scarce minerals known as the "rare earths." They are the following: cerium, dysprosium, erbium, gadolinium, holmium, lanthanum, lutecium, neodymium, praseodymium, samarium, scandium, terbium, thulium, ytterbium, (neoytterbium), yttrium.
It should be noted that this group of metals does not contain all the "rare" metals, but only those specifically derived from "rare earths." Metallic radium, for instance, which is excessively rare, is not a member of the rare-earth group of metals.